This study is about the evaluation of non-immersive desktop web-based photo-realistic virtual environments using think-aloud protocol and heuristic evaluation to determine three aims: (1) whether applying the same usability evaluation methodologies result in additional usability guideline categoriesidentified from the Koykka, Ollikainen, Ranta-aho, Milszus, Wasserroth and Friedrich 1999 study; (2) whether think-aloud protocol or usability heuristic evaluation is a better evaluation method for identifying usability problems in desktop, photo-realistic virtual environments; and (3) whether large-scale desktop, photo-realistic virtual environments will have more usability problems than small-scale non-immersive, desktop, photo-realistic virtual environments. The results show that using the Emergent Theme Analysis (ETA), four broad themes were derived: functionality, interaction, appearance and user comments with functionality and interaction broad themes being similar to the categories suggested by Koykka et al. (1999). Furthermore, the results indicate that small-scale non-immersive, desktop, photo-realistic virtual environments had more usability problems than large-scale non-immersive, desktop, photo-realistic virtual environments, contrary to the hypothesis that large-scale VEs will have more usability problems due to its complexity and that the think-aloud protocol derived more themes compared to the heuristic evaluation – suggesting that TAP is a better usability evaluation method than HE in this type of study. However, a combination of the two qualitative methods has identified a greater number of usability problems, supporting the need for triangulation of research methods. The investigation resulted in new design guidelines that will allow for more usable design of non-immersive desktop, photo-realistic virtual environments. Furthermore, the study provides some new areas for future developments of usability evaluation methods for non-immersive desktop, photo-realistic virtual environments.